A069661 Smallest n-digit prime with maximum digit sum.

7, 89, 997, 8999, 98999, 989999, 9899999, 89999999, 998999999, 9899989999, 98999999999, 999998999999, 8998999999999, 99899999999999, 999999899999999, 9998999999999999, 99999999999899999, 999998999999999999, 9998999999999999999, 89999999999999999999

Offset: 1

Author

Amarnath Murthy, Apr 05 2002

Keywords

• nonn
• base

Crossrefs

a(n) = A069662(n) for these n <= 20: 1, 2, 3, 4, 6, 7, 9, 17 and 19. a(5) = Reverse(A069662(5)).

Programs

Mathematica

Table[max=0; Do[p=Prime[i]; If[Total[IntegerDigits[p]] > Total[IntegerDigits[max]], max=p], {i,PrimePi[10^n]+1, PrimePi[10^(n+1)]}]; max, {n,0,7}] (* Jayanta Basu, May 19 2013 *)

Extensions

Corrected and extended by Rick L. Shepherd, Jul 15 2002. a(5) through a(20) have been certified prime with Primo.